Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
Are you entering the amazon app to get to the Starz ch on the Roku 3 as you have to if you're paying for it through amazon on the Ultra. The Stand Alone Starz app on Roku home screen is for those who pay Starz Directly, not for those who pay through third party like Roku, Amazon, and many others.
We pay the cable company Charter Spectrum for all the Premium movie channels. When viewing in Amazon Prime app on the Roku 3 it’s like it doesn’t recognize we are already paying for it. I’ve tried putting the code in and it won’t take it. However, the Roku Ultra on another TV does recognize it.
For more information about that channel's features and functionality, you'll want to contact [specific channel] support directly to inquire further. Many channels on Roku are developed and maintained by the channel provider themselves.